Various embodiments of the present disclosure relate to a charging device, and more particularly to a wireless charging device.
In general, a mobile terminal, such as a portable electronic device, includes a rechargeable battery pack. Typically, the battery pack of the mobile terminal is charged using a separate charging device that plugs into the mobile terminal.
Separate contact terminals are generally provided on the outside of the charging device and the battery pack so that the charging device and the battery pack can be electrically connected to each other. However, because the contact terminal is exposed to the outside in the contact type charging method, the battery pack may not be properly charged when the contacts are contaminated by foreign substances. Further, the battery pack may not charge properly when the contact terminal is exposed to moisture.
In order to solve the above-mentioned problems, wireless charging, or non-contact charging, technologies have recently been developed and have been utilized for a number of portable electronic devices. The wireless charging technology uses wireless power transmission and reception that automatically charges a battery pack as long as a portable electronic device is positioned on the charging pad with no need to connect a separate charging connector to the portable electronic device.
The wireless charging technology generally uses an electromagnetic induction scheme using a coil, a resonance scheme using a frequency resonance, or an RF/microwave radiation scheme that converts electrical energy to microwave and then transmits the microwave.
Up to now, the electromagnetic induction scheme has been considered mainstream, but it is expected that in the near future all electronic products will be wirelessly charged, anytime and anywhere, based on recent successful experiments for wirelessly transmitting power to a destination that is separated by dozens of meters using microwaves.
The resonance scheme uses the same physical concept of resonance that can lead to a wine glass breaking if its resonant frequency is the same as a tuning fork that is struck. For wireless charging, instead of resonating sounds, the resonance of electromagnetic waves containing electrical energy is used to remotely transfer electrical energy from the charger to the battery pack. It is known that resonant electrical energy does not affect surrounding machines and human bodies any more than other electromagnetic waves because the resonant electrical energy is directly transferred to a device that has the same resonant frequency and its unused part is reabsorbed into an electromagnetic field instead of spreading.
The wireless charging device using a resonator according to the related art includes a transmission resonator and a wireless power transmission device. The wireless charging device includes a transmission resonator that provides charging power from a wireless power transmission device and a wireless power transmission pad containing a metal plate or a magnetic shield member at a predetermined interval from the transmission resonator.
That is, the wireless charging device using the resonator adopts a method of positioning an electronic device on a wireless power transmission pad to charge the electronic device.